fixed SeqPath itemSliceClass setting by moving it to the __init__ from __getitem__. This correctly handles many additional cases is __neg__, __add__ etc.
fixed SeqPath itemSliceClass setting by moving it to the __init__ from __getitem__.
This correctly handles many additional cases is __neg__, __add__ etc.

cjlee112/pygr,RitwikGupta/pygr,theoryno3/pygr,cjlee112/pygr,GenDataPro/pygr,ctb/pygr,cjlee112/pygr,GenDataPro/pygr,theoryno3/pygr,RitwikGupta/pygr,ctb/pygr,ctb/pygr,cjlee112/pygr,ctb/pygr,RitwikGupta/pygr,ctb/pygr,GenDataPro/pygr,theoryno3/pygr